first up - my problem is with an APM 2.5 clone (arduflyer) - I know some of you don't want to assist with hardware not bought from 3dr store (which is fine) so I'll make this point clear at the beginning so you can stop reading. 

If you're still reading.

I'm experiencing connection problems with my APM 2.5 clone.

Some background: I received it a few days ago, connected it to the latest version of mission planner without problems and loaded 2.9 firmware on it (for Hexa). Did acc & compass calibration, radio calibration, GPS and telemetry modules. Everything seemed to work. After reading some reports of people experiencing problems with 2.9 I decided to downgrade to 2.8.1. before setting up the motors etc.

Did the downgrade and a reset. Everything seemed to work.

Then I did a few more bench tests the following day. I connected 5V from a UBEC to the board and connected  from Mission Planner  via the 433 Mhz telemetry radios. This seemed to work. Then I connected the GPS. This also worked but I received quite a few error messages such as "Parameter XXXX already set" (for different parameters XXXX) and eventually a connection error.

I tried this a few time with and without GPS with varying success. I ended up having the arduflyer board with just the radios on my desk and I could connect and disconnect successfully on a few occasions. Sometimes I would get the "Parameter XXXX already set" errors. After one of the tries where I received these errors I clicked on disconnect and then on connect and I didn't get a connection anymore. After a while I got a timeout saying that no Hearbeats had been received.
I clicked connect a few more times - same error. Note that the 433 MHz radio LEDs indicated that the radios were connected.

Then I tried to connect again via the USB cable. No success - same error. I haven't been able to talk to the clone board since. When I plug it into the PC it shows up as COM 4 Arduino 2560. However, I can't communicate with it through Missionplanner or the Arduiono IDE. I can't upload new firmware using MP or any sketch with Arduino. CLI in MP also doesn't work. When I try to initiate USB port communication with the board it appears to reset (LEDs A and C flash rapidly a few times, then do cylic flashing for a few seconds and finally the red LED blinks slowly).

I spent quite a bit of time reading here and elsewhere and found some threads with similar but not identical issued. I've reinstalled Mission Planner, USB-Serial drivers etc. to no avail.

Based on how it happened I am almost 100% confident that I didn't fry the board by connecting something wrongly (reverse polarity or too high voltage). I think the error is something more subtle - either a flaky component or some software problem.

If it is a hardware bug I suspect it is somewhere in the Auto-MUX circuit that switches between USB and radio telemetry.

Otherwise, could I have somehow "killed" my Arduino bootloader through a software bug? I don't see how but I do have an USBAsp AVR programmer at hand and I could try reflashing the boot loader.

I also contacted the vendor (only a couple of hours ago - so wouldn't expect a response yet) but even if they offer to fix it - due to shipping times from and back to Europe I'd vastly prefer it if I could somehow diagnose and fix this myself in the coming days. 

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  • Did you get a resolution? I think I have the same problem....

    My APM 2.5 (from RCTimer) is very new and I have flown it in my Bixler2, tested Stabilise, Loiter & RTL.

    Finally did a mission today and all worked fine until I tried to download the logs.

    Now I cannot communicate via USB or by 915Mhz module, but I could earlier the same day! (both ways)As I cannot reach CLI / Terminal window, I cannot reset the board.

    I am running at the correct baud rates, because some of the text is readable eg: ArduPlane 2.7b comes up but the 3x Enter keys do not work.



    worst day of my flying "career"




    I had an ESC wich wouldnt start due to the outside temperature.


    Yesterday was a beautiful day to test the new software for my APM2.5. So I went outside, and the darn ESC acted up again. So I hurried back inside to exchange the ESC for another one. That took me a few hours because of my construction.


    When I switched on the copter, I saw a tiny stream of smoke. At first I thought it was a hair from the cat floating into focus, but it wasn't. After that no communiction with USB anymore. The system is still alive, I get GPS lock The RX/TX leds blink when communicating with something else than the USB port. But I dont have PPM anymore and no USB. I think the USB input of the atmega32u2 is fried. Now for a way to desolder and resolder a new chip.


    The cause of my trouble was a faulty, NEW, speed controller. The voltage out of the BEC was 8.5V and fried (only) the atmega 32U2?


    I still dont know where the smoke came from, which wouldt make it easier to repair the APM.


    The 2 VDR's on the input of the USB port are still ok, as are the two fuses.


    I didnt check the zener yet but I think it will be ok also.




    In the meantime I have ordered a new APM2.5 board, this time in china, because 3d-robotics is too expensive, and they send you a box (which weighs 20 grams) with the price on the outside, so dutch customs hits you with an additional very expensive tax. (why Oh why not send it in a closed envelope!!)




    Bye for now,


    a very sad Wilfred.

  • Try going back to 2.9, might be a change to the latest MP (that 2.8.1 doesn't like).

    woops, read half your post.. my guess is you wiggled something loose on one of your connectors.

  • Moderator

    Have you tried USB with the radios unplugged?

  • Admin


    You will probably not get much sympathy here. Most of the cloners probably use the cheapest parts and processes that are available to maximize their profits. Quality control is everything and you are probably a victim of the lack of it by the cloner you bought from.

    Just a thought.



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